JPS62297499A - Method for evaluating uniformity in thickness of plated film during electroplating - Google Patents

Abstract

PURPOSE:To evaluate uniformity in the thickness of plated films during electroplating by applying voltage between electrically conductive patterns formed on an insulating subtrate and an electrode to carry out electroplating and by measuring electric currents generated in the patterns. CONSTITUTION:Voltage is applied between the pad terminals 8a-8d of an insulating substrate 6 and an electrode 12 from a power source 13 to carry out plating on electrically conductive patterns 7a-7d and the terminals 8a-8d. During the plating, electric currents Ia-Id generated in the patterns are measured with ammeters 14a-14d, and the thickness (t) of each deposited thin metallic film is calculated by the formula (where a is a constant depending on the kind of metal, I is electric current generated by applied voltage and S is plating area). Uniformity in the thickness of thin metallic films is evaluated according to the calculated thickness (t).

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for evaluating the plating film thickness of a conductive pattern in an electroplating method.

(Prior Art) Conventionally, in an electroplating method in which an electrode and a sample are immersed in an electrolytic solution containing metal ions and a voltage is applied to both, a desired metal thin film is deposited on the surface of the sample to be processed.
It is very important to obtain an F14 thin film with a uniform thickness on the surface to be processed. The thickness uniformity of a thin metal film is controlled by many factors, such as the shape of the electrode, the distance between the electrode and the surface to be treated of the sample, the voltage applied to both, and the uniformity of the metal ion concentration in the electrolyte. Conventionally, conditions for these factors for improving thickness uniformity have been determined by measuring the film thickness of an actually formed metal RG film, as described below.

4th rl! J is the surface to be processed of the sample, in which the conductive paste layer (hereinafter referred to as the plated surface) on which the metal film is formed by electroplating is exposed in the area (1), and the area (2) is the plated surface (1). is covered with resist, preventing the formation of a metal film due to electroplating. A sample is created by exposure and development. FIG. 5 shows a side sectional view of a sample subjected to electroplating. (3) is the electroplated surface, (4) is the resist, and (5) is the gold w4I formed by electroplating.
! ! It is 4. Figure 6 is a diagram with the resist (4) removed, and the metal Jl! J (5) Thickness 1. , 12.13...
1. The uniformity of the thickness of the metal film can be evaluated by determining , over the entire surface to be processed using a stylus type M thickness meter.

(Problems to be Solved by the Invention) As mentioned above, there are many factors that contribute to the uniformity of the film thickness of a metal thin film formed by electroplating, and it is necessary to improve the uniformity of the film thickness with respect to these factors. In order to determine the optimal conditions for electroplating, it is necessary to evaluate thick film uniformity for a number of electroplating conditions. However, in the conventional film thickness uniformity evaluation method, one sample is evaluated in accordance with one electroplating condition, and thus electroplating must be performed multiple times. Therefore, this method requires a large number of man-hours and a large number of samples, which is both inefficient and uneconomical. In addition, it takes a lot of man-hours to remove the resist and measure the film thickness after electroplating, and it is impossible to understand the deposition and deposition status of the thin metal film during electroplating, so we carefully examine the electroplating conditions. In addition, it is difficult to discover new factors contributing to film thickness uniformity.

This invention eliminates the above-mentioned inefficiency and uneconomical effects, solves the problem of not being able to grasp the deposition and deposition status of a metal thin film during electroplating, and sets optimal electroplating conditions that improve film thickness uniformity. The present invention provides a method for evaluating plating film thickness uniformity.

(Means for Solving the Problems) This invention applies a voltage to a plurality of conductive patterns formed on an insulating substrate and a counter f4 electrode in order to evaluate the uniformity of plating film thickness in electroplating. By electroplating the conductive pattern and measuring the current generated in the conductive pattern, the plating film thickness distribution can be evaluated at the same time as electroplating.

(Function) As described above, this invention performs electroplating by applying voltage to a plurality of patterns and counter electrodes, so that it can be applied on an insulating substrate based on the interrelationship between the deposited plating thickness and the current and area. This makes it possible to evaluate the uniformity of plating film thickness.

(Example) Figure 1 is a plan view of a sample used to evaluate the uniformity of plating film thickness in the present invention. A plurality of conductive patterns (7a) to (7d) are formed, and pad terminals (8a) to (8) for voltage application are formed on each conductive pattern.
d) form. Each of these conductive patterns: / (7a)
The total area obtained by adding the area of pad terminals (8 m) to (8d) to the area of ~(7d) is S, ~S. Figure 2 shows an example of the method for evaluating the uniformity of plating film thickness, in which an electrolytic solution (11) containing desired metal ions is contained in a plating tank (9). The above insulating substrate (6
) and electrodes (l), and connect the conductor α1) to each pad terminal (8a) to (8d) of the board (6), and the conductor (l1m) to the electrode (11).Both conductors (ill, (l)
1m) between which there is a power source (1 meter) and a voltmeter (1 meter) for voltage application.
'9 are connected in series and ammeters (14m) to (14d) are connected in parallel.

Thus, the above 'r! The insulating substrate (6
), a voltage is applied between each of the pad terminals (8a) to (8d) and the electrode θ4, and plating is performed on the conductive patterns (7a) to (7d) and the pad terminals (8a) to (8d). At this time, the currents measured by the ammeters (14m) to (14d) are assumed to be (1) and (6) to (6). Add to this a constant that depends on the metal type, ■
is the current generated by the applied voltage, and S is the plating area. Note that a is determined in advance by experiment. As a result of the above, I, /S,.

By determining Ib/S, I, /Sc, and Id/S, the uniformity of the metal thin film can be evaluated from the above equation t=a·I/S. Therefore, it goes without saying that it is possible to form a pattern as shown in FIG. 3 in accordance with the desired film thickness distribution and perform the same evaluation as described above.

(Effects of the Invention) As explained above, according to the present invention, electroplating is performed by applying a voltage between a conductive pattern formed on an insulating substrate as a sample and an electrode, and the current generated in the pattern is measured. Since the plating film thickness distribution is evaluated, (a) the uniformity of the plating film thickness of the insulating substrate can be evaluated while performing electroplating.

(b) (The advantage of Al is that the Ti9F% plating conditions can be changed in real time to determine the optimal conditions for achieving good uniformity of the plating film thickness.

(c) Evaluation of plating film thickness uniformity does not require completion of electroplating and can be completed in a short time.

(d) It is possible to reuse the sample and it is economical.

(It is not necessary to process the sample or measure the film thickness after eJ plating, and (combined with the advantages of C1, it is very efficient, and the number of man-hours required for setting electroplating conditions can be significantly reduced.

(f) If the above evaluation method can be implemented on the actual workpiece,
The present invention can also be applied to an electroplating apparatus that applies feedback during electroplating to make the current density uniform on the plating surface of the object to be processed, thereby making it possible to obtain a plating film thickness.

[Brief explanation of the drawing]

Figure 1 is a plan view of a sample for evaluating the uniformity of plating film thickness, Figure 2 is a configuration diagram of the plating equipment, Figure 3 is a plan view of a conductive pattern, Figure 4 is a plan view of a conventional sample, and Figure 4 is a plan view of a conventional sample. Figure 5 is the fourth
rI! 6 is a side view of FIG. 5 with the resist removed.
7a) to (7d) - conductive pattern, (8a) to (8d
)...Pad terminal, (9)...Plating bath, (1ω・
... Electrolyte, (la... Electrode, (14a) to (14d
)...Ammeter, (eye/voltmeter. Figure 2 Figure 3)

Claims (1)

[Claims] A plurality of conductive patterns are formed on an insulating substrate, and a voltage is applied to each of these conductive patterns and a counter electrode to perform electroplating on the conductive patterns. At this time, plating is performed by measuring the current generated in each conductive pattern. A method for evaluating plating film thickness uniformity in electroplating, characterized by evaluating film thickness distribution.